This invention relates to a process wherein H.sub.2 S is selectively removed in a minimum two stages of gas-liquid scrubbing from gas streams containing H.sub.2 S and CO.sub.2 with little or no CO.sub.2 removal.
The selective removal of H.sub.2 S from CO.sub.2 in gases containing them and the use of alkaline salt solutions for H.sub.2 S and CO.sub.2 adsorption is generally known from "Gas Purification" by Kohl and Riesenfeld Third Edition (1979) Chapters 4 and 5.
The removal of H.sub.2 S gas from refinery gas streams by contacting the gas stream with basic alkali metal sulfide solutions in a single contactor is known from U.S. Pat. No. 2,662,000. However, the use of this technology with a gas stream containing both H.sub.2 S and CO.sub.2 gases results in the precipitation of insoluble sodium carbonate and the fouling of the equipment and inefficient use of alkalinity.